I have had a question today as why when they put in 6 fertile eggs, after 23 days upon checking 1 was just a yolk and 5 were fully formed but did not hatch, what is the problem. I am afraid the problem is caused by too much humidity in the incubator, only 5 of the eggs were fertile eggs the other was a dud but of the 5 that did develop there was not enough loss inside the egg shell due to incubator humidity and with a chick developing to large it was unable to turn to break out of the shell. I would suggest a new batch of eggs and maybe 50% less water than the last incubation, ideally have the incubator have water in only every other day so 1 day in 2 it is dry. Then of course plenty of humidity for the last 2 days. I hope this helped you Peter